tailieunhanh - Modeling and Simulation for Material Selection and Mechanical Design Part 12

Tham khảo tài liệu 'modeling and simulation for material selection and mechanical design part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | and the workpiece under test to the short-time tensile yield strength of the softer contact body at the test temperature. The value of t is simply a measure of the resistance of the joint to shear. The friction condition at the surface of a cutting tool will be similar to that for which the value of t was measured. The results of the wear resistance tests are given in Fig. 6. As can be seen the wear resistance of HSS tools is times lower than that of DCPM tools. This reduction was associated with a significantly lower friction parameter of DCPM compared to HSS Fig. 7 and a broadening of the range of normal friction Fig. 6 . Within the normal friction range the rate of wear for DCPM is much lower than that for HSS Fig. 6 curves 1-3 . While the hardness and heat resistance values of the HSS T15 and DCPM are similar the wear resistance of the latter is significantly higher Table 3 . In our opinion the lower wear intensity of the DCPM-tool material is related to the presence of titanium carbides in the structure and their subsequent transformation to oxygen-rich compounds during cutting. When studied by secondary ion mass spectroscopy SIMS the analysis of typical wear craters revealed the formation of oxygen-containing phases. The data in Fig. 8 demonstrate that the transformation of titanium carbide into an oxygen-containing phase starts in the initial stage of wear during the running-in process Fig. 8a . With further operation there is increased surface oxide formation at the bottom of the wear crater. This process is accompanied by stabilization of the wear processes Fig. 6 and 8b c and an expansion of the normal friction range. Evidently this is determined by the phenomenon of self-organization that is connected with the emergence of secondary structures titanium-oxygen compounds which play the role of stable solid lubricants 25 . Figure 6 The dependence of the flank wear value of cutting tools on the cutting time 1 HSS M2 2 HSS T15 3 DCPM. Turning test .